The present invention relates to universal joints for use in the driveline of a motor vehicle. In addition, the present invention relates to a method for assembling universal joints.
As is well known, universal joints are used in motor vehicle driveline applications for interconnecting a pair of rotary shafts and permitting changes in the angularity therebetween. Most conventional universal joints include a pair of bifurcated yokes which are secured to the shafts and which are interconnected by a spider or cruciform for rotation about independent axes. The cruciform includes four orthogonal trunions with each opposing pair of axially aligned trunions mounted in a pair of aligned bores formed in the bifurcated yokes. Typically, a bearing cup is secured in each bore and a bearing assembly is retained in the bearing cup such that each yoke is supported for pivotal movement relative to a pair of trunions.
Although it is known that misalignment of the rotary axes of the rotating shafts may result in a unbalanced universal joint, various retention methods have been developed for securing the bearing cups to the yokes in a manner wherein the rotary axis of each yoke is aligned centrally with respect to the rotary axis of the cruciform. Traditional bearing cup retention methods include the use of grooves and snap rings, plastic injection and staking. However, each method has one or more disadvantages such as, for example, excessive machining requirements, limited serviceability, and the inability to compensate for tolerance variations of the components. In particular, one type of conventional universal joint utilizes snap rings which are seated in circumferential grooves machined into the bores formed in the yokes for axially positioning the bearing cups. However, in determining the desired location of the grooves, the sum of each component's dimensional variation (i.e., stack-up) must be taken into consideration. As such, a compromise occurs between the allowable manufacturing tolerances of the individual components and the desired component alignment. Other universal joints attempt to compensate for dimensional variations in the components but sacrifice serviceability. Specifically, the plastic injection processes is well-suited for use in production assembly environments but is impractical for servicing universal joints in the field. Several examples of bearing cup retention arrangements and methods associated with conventional universal joints are disclosed in U.S. Pat. Nos. 3,062,026, 3,178,907, 3,701,189, 3,986,238, 4,000,628, 4,310,206 and 4,704,782.